Chapter 3 : Distributed Data Processing Business Data Communications, 6e

Centralized Data Processing Centralized computers, processing, data, control, support What are the advantages? Economies of scale (equipment and personnel) Lack of duplication Ease in enforcing standards, security

Centralized Data Processing May Consist Of: Centralized Computers Centralized Processing Centralized Data Centralized Control Centralized Support Staff

Distributed Data Processing Computers are dispersed throughout organization Allows greater flexibility in meeting individual needs More redundancy More autonomy

Why is DDP Increasing? Dramatically reduced hardware costs Dramatically increased distributed processing capabilities Dramatically increased need for new applications and shorter development times Ability to share data across multiple servers

DDP Pros & Cons There are no “one-size-fits-all” solutions Key issues How does it affect end-users? How does it affect management? How does it affect productivity? How does it affect bottom-line?

Benefits of DDP Responsiveness Availability Correspondence to Org. Patterns Resource Sharing Incremental Growth Increased User Involvement & Control Decentralized Operation & Control End-user Productivity Distance & Location Independence Privacy & Security Vendor Independence Flexibility

Drawbacks of DDP More difficulty test & failure diagnosis More dependence on communication technology Incompatibility of components Incompatibility of data More complex management & control Difficulty in control of corporate information resources Suboptimal procurement Duplication of effort Data integrity Security

Client/Server Architecture Combines advantages of distributed and centralized computing Cost-effective, achieves economies of scale Flexible, scalable approach

Intranets Uses Internet-based standards & TCP/IP Content is accessible only to internal users A specialized form of client/server architecture Can be managed (unlike Internet)

Extranets Similar to intranet, but provides access to controlled number of outside users Vendors/suppliers Customers Utilizing Web technologies

Distributed applications Vertical partitioning One application dispersed among systems Example: Retail chain POS, inventory, analysis Horizontal partitioning Different applications on different systems One application replicated on systems Example: Office automation

Other Forms of DDP Distributed devices Network management Example: ATM machines Network management Centralized systems provide management and control of distributed nodes

Distributed data Centralized database Replicated database Pro: No duplication of data Con: Contention for access Replicated database Pro: No contention Con: High storage and data reorg/update costs Partitioned database Pro: No duplication, limited contention Con: Ad hoc reports more difficult to assemble

Networking Implications Connectivity requirements What links between components are necessary? Availability requirements Percentage of time application or data is available to users Performance requirements Response time requirements

Database Management Systems Structured collection of data for multiple applications to use Query language provides uniform access

Database Organization Centralized – Common databases accessed by all processors Replicated - Copy of central database stored at each processor Partitioned – Individual databases for each processor

Centralized Databases Advantages No duplication of data Little reorganization required Disadvantages Contention among multiple processors accessing a single database Slow response time Single point of failure

Replicated Databases Advantages No processor-database contention Shorter response time During failure, new copy can be obtained Disadvantages High storage cost Redundant updates required High reorganization costs

Partitioned Databases Advantages No duplication of data Size of database determined by application needs Short response time Disadvantages Ad hoc management reports must access multiple databases

Networking Implications What are the connectivity needs? What are the availability needs? What are the performance needs?